Newmilns and Greenholm is a small burgh in East Ayrshire, Scotland. It has a population of 3,057 people (2001 census) and lies on the A71, around seven miles east of Kilmarnock and twenty-five miles southwest of Glasgow. It is situated in a valley through which the River Irvine runs and, with the neighbouring towns of Darvel and Galston, forms an area known as the Upper Irvine Valley (locally referred to as The Valley). As the name suggests, the burgh exists in two parts - Newmilns to the north of the river and Greenholm to the south. The river also divides the parishes of Loudoun and Galston, which is why the burgh, although generally referred to as Newmilns, has retained both names.

Newmilns means "the new mills", from Old English niwe "new" and myln "mill", the name being recorded as Nawemeln in 1126 - the plural Newmilns is a recent addition.

At the end of the 16th century, refugees from France and Flanders settled in Newmilns, bringing with them skills and techniques in lace making. Most houses had a loom by the end of the 18th century. The introduction of the power loom in the late 19th century marked the beginning of the golden years for the lace industry in Newmilns. By the end of the Second World War, there were 12 lace and madras factories in Newmilns. The importance of lace is reflected in the architecture of public buildings in the town centre, such as Lady Flora's Institute and the Morton Hall.

The subsequent decline of lace making in the town, due to growing competition from overseas, led to a decline in the fortunes of Newmilns. Town centre buildings fell into disrepair and an aura of dereliction and depression led to historic properties becoming uninhabitable, roofless or being demolished. From 1999 to 2005 a Heritage Lottery Fund-supported project known as the Newmilns Townscape Heritage Initiative carried out extensive building restoration and renovation works, including the environmental improvement of open space and waste ground in Newmilns and reinstatement of architectural detail and features.

Newmilns Tower (which once had impressive gardens and orchards surrounding it), was erected in the centre of the town about 1525 by Sir Hugh Campbell, Earl of Loudoun. Newmilns Tower was built following the destruction of Loudoun Castle by the Kennedys of Culzean, during which Sir Hugh's wife and nine children were all killed. The attack was apparently in retaliation for the role Sir Hugh had played in the murder of a kinsman of the Kennedys. The Earls of Loudoun continued to reside at Newmilns Tower until 1615. It is sometimes suggested that the Earls of Loudon later built what is now the Loudoun Arms as a town house.

Newmilns Tower saw further use in the religious wars of the mid 1600s as a prison for Covenanters. Some of the prisoners held here were freed in a raid on the tower, but at least one was killed during the escape.

The tower was fully restored by the Strathclyde Building Preservation Trust in the 1990s and is now a privately owned residence.